Conventionally, there is an information processing apparatus that has an electronic mail (hereinafter referred to as “mail”) sending and receiving function. The above-described information processing apparatus may be, for example, a Personal Computer (PC), a Personal Digital Assistants (PDA), or a mobile phone terminal.
In a field of the personal computer, there has been a mailer that sends an already-read mail indicating that the mail is read to a sending source of the mail when the mail is read at a sending destination of the mail. A mailer is software that generates, sends, receives mail, and stores and manages received mail. Japanese Laid-Open Patent Publication No. 2003-44416, for example, has been known as a conventional technique.
In the above-described conventional technique, by receiving the already-read mail, the sending source of the mail is able to know that the mail is read in the sending destination of the mail. However, the sending source is unable to know whether or not a reply mail responding to the mail is being edited.